Spectrin and a cAMP-independent protein kinase have been isolated from sheep erythrocyte ghosts by modifications of standard methods. The rates of phosphorylation of spectrin by the erythrocyte kinase and by a kinase from Acanthamoeba castellanii that phosphorylates the heavy chain of Acanthamoeba myosin I have been compared. Possible effects of the phosphorylation of spectrin by the two enzymes are being measured.